body {
    overflow-y: scroll;
}

.navbar-brand {
    padding: 5px;
    margin-right: 50px;
}

.navbar-nav li {
    margin: 0 5px;
    font-size: medium;
}

.navbar-nav li:hover {
    background-color: rgb(230, 230, 230);
}

.main-content .row {
    padding: 20px 0;
}


/* 大标题 */

h1 {
    font-size: x-large;
    margin: 30px 0;
}


/* 小标题 */

h2 {
    font-size: medium;
    color: rgb(125, 125, 125);
}


/* 段落标题 */

h3 {
    font-size: large;
    margin: 30px 0;
    font-weight: bold;
}

h3::before {
    content: '【';
}

h3::after {
    content: '】';
}


/* 段落正文 */

p {
    font-size: larger;
    margin: 20px 0;
}


/* 链接 */

p a {
    font-style: normal;
    text-decoration: underline;
    color: rgb(28, 28, 207);
}


/* 强调 */

em {
    font-style: normal;
    color: rgb(250, 41, 128);
}


/* 图像框 */

.img-box {
    text-align: center;
    margin: 20px 0;
}

.img-box img {
    width: auto;
    height: auto;
    max-width: 100%;
    max-height: 100%;
}

.img-box h4 {
    margin: 10px 0;
    font-size: medium;
}


/* 视频框 */

.video-box {
    text-align: center;
    margin: 20px 0;
}

.video-box video {
    width: auto;
    height: auto;
    max-width: 100%;
    max-height: 100%;
}

.video-box h4 {
    margin: 10px 0;
    font-size: medium;
}